Pre-op fasting / Sawm qabel l-anestesija

Although fasting before anaesthesia entails a significant effort and sacrifice on the part of the patient who is preparing for a procedure, investigation or surgery, it is essential in order to minimise the volume of stomach contents and reduce stomach acidity. This is of great importance because during general anaesthesia or sedation there can be regurgitation (upward movement) of these contents, with the associated risk of pulmonary aspiration. Pulmonary aspiration, of even small amounts of stomach contents, has been associated with serious and sometimes life-threatening complications, including airway obstruction, an inflammation of the lining of the lung, known as pneumonitis, development of chest infection, respiratory failure, and unexpected admission to intensive care. The aim of pre-operative fasting, that is the planned witholding of both solid food and fluids, is therefore to minimise stomach contents and therefore lessen the risk that these pose during anaesthesia.

The pre-operative fasting period depends on the type of food and fluids consumed, as well as the timing of the procedure (whether it will happen in the morning or in the afternoon). Solids, milk and milk-containing drinks (more than one-fifth containing milk) should not be consumed within 6 hours of the start of an operation (milk curdles in the stomach and becomes a solid). One should avoid heavy or fatty meals pre-operatively, even on the eve of surgery, as these food contents remain in the stomach for much longer (> 8 hours), being slower to digest than other foods. Sweets and chewing gum are viewed as solids and should not be taken for 6 hours prior to the start of the procedure. Still water should be allowed and indeed encouraged up to 2 hours before anaesthesia. This same recommendation also applies to clear fluids. A clear fluid is one where newsprint is visible through a glass of the liquid. These include water, fruit squash, black tea or black coffee, diluted juices and non-fizzy energy drinks. Carbonated beverages should be discouraged before anaesthesia. Clear fluids should not contain alcohol or pulp (pieces of fruit). Water actually encourages stomach emptying and a small volume of water (a few sips) may be given with the patient’s usual medication or with a pre-medication tablet up to 30 mins before anaesthesia.

At pre-operative assessment, one should be made familiar with the hospital’s pre-operative fasting guidelines, and should be given the necessary and specific information in this respect, ideally also in written form or by means of a printed patient information leaflet. One should also be given sufficient opportunity to ask questions and clarify any misunderstandings that one might have in this respect. The guideline, included in table form at the end of this article, follows what is now described. For a morning surgery or procedure, one should be fasted and ready for anaesthesia at 8:30AM. This means that no solids should be consumed after midnight (24:00h). You can drink water or clear fluids in moderation until 06:30AM. Most patient information leaflets now recommend drinking water only 2 hours before surgery requiring anaesthesia, in order to simplify instructions and prevent cancellation of surgery due to ingestion of unacceptable fluids by mistake (e.g. erroneously taking tea with milk at 6:30AM). In the case of an afternoon procedure, one should be fasted for anaesthesia to start at 13:00h. This means that a light breakfast should be allowed before 07:00AM, and no solids should then be consumed after that time. Examples of a suitably light breakfast include a small bowl of cereal (not high in fibre) with skimmed or semi-skimmed milk, or a slice of toast and a cup of tea, coffee, or fruit juice. No high fibre cereals such as bran, weetabix or muesli should be consumed, and fatty foods such as cold meats or fried food should be avoided. Still water should again be encouraged up to 2 hours before the procedure i.e. up to 11:00AM. If one is to have surgery as part of a long operating list, and one happens to be the last case or the one before the last on the list, it is good practice to avoid unnecessarily prolonged fasting by considering and managing such a case as an afternoon case (i.e. light breakfast before 07:00AM, no solids thereafter, and still water until 11:00AM).

There are many risk factors that may delay stomach emptying and also increase the chance of regurgitation and subsequent aspiration, while under anaesthesia or sedation. These include obesity, gastro-intestinal pathology such as gastro-oesophageal reflux and hiatus hernia, renal failure, diabetes mellitus, anxiety, trauma, neurological disease and pregnancy amongst others. When your anaesthetist recognises such an increased risk , you may be prescribed certain medications to decrease stomach acidity, and you might also be instructed to withold water for a greater period of time ahead of your procedure (>2hours).

Children should be scheduled at the start of lists, with the youngest going first, in order to minimise starvation times as much as possible. No solids, milk, or cow’s milk, should be given for 6 hours prior to anaesthesia. No breast milk should be given for 4 hours before anaesthesia. Clear fluids may be given up to 2 hours before the procedure.

Women in labour are considered to be at increased risk of gastro-oesophageal reflux. If they have a favourable obstetric history, and are planned for a normal delivery, having a low risk of requiring obstetric intervention, they may be allowed to eat and drink during labour. Again, avoiding large, heavy or fatty meals and carbonated beverages, during this time is advisable and considered to be good and safe practice. In the case of a higher risk pregnancy (including those women who have an epidural inserted for pain relief during labour), women should be encouraged to drink clear, still fluids only. Women scheduled for planned caesarean section should be starved as per normal pre-operative guidelines (no solids or milk for 6 hours prior to anaesthesia, still water up to 2 hours before).

If you are having a procedure under regional anaesthesia (spinal, epidural or peripheral nerve block) you should be fasted as for a general anaesthetic. This is because you might require additional sedation or more uncommonly conversion to a general anaesthetic.

If you require local anaesthesia only, you will be instructed that no period of pre-operative fasting is required, and you may therefore eat a normal diet on the day of surgery.

If one is scheduled to receive intravenous sedation for a procedure (e.g. gastroscopy or colonoscopy) or minor surgery, this again necessitates that one is fully fasted pre-operatively, as already outlined above and as described in the below guideline.

In the case of urgent or emergency surgery, whenever it is advisable and possible, this should be delayed in order to allow the fasting times to be adhered to. When this is not possible, and the urgency of the procedure takes precedence, your anaesthetist should be adequately informed beforehand, and will modify the anaesthetic technique in order to lessen the risk of regurgitation of stomach contents.

One must also mention a point, and mostly directed at healthcare personnel, that fasting advice and guidelines also have the aim of lessening the incidence of unnecessary or prolonged fasting before surgery. This is very unpleasant for patients and may result in dehydration (especially during the summer period), hypoglycaemia (particularly in diabetics), electrolyte abnormalities, irritability (usually in children), anxiety, increased nausea and vomiting, and confusion (especially in the elderly). Where patients have been fasted for fluid for over 6 hours, it is a good idea for ward staff to contact the anaesthetist, to ask whether it would be acceptable or advisable for the patient in question to have a drink of still water, or as to whether an IV fluid infusion should be started.

Adults and children should generally be allowed to resume drinking as soon as they wish, and feel able to, following planned surgery. Normal fluid intake however need not be insisted upon before allowing discharge from a day surgery facility.